The present invention relates generally to apparatus and methods for aligning and placing insulators, such as wedges, along slots of a magnetic core of a dynamoelectric machine.
Different types of dynamoelectric machines utilize insulating material of suitable dielectric strength for insuring that two or more different parts of such machine remain electrically insulated from one another.
For example, in many constructions, ground or cell insulation is frequently provided along the walls of slots in magnetic core members, and windings of a first phase are disposed along the insulated slots. In those instances where winding turn portions of a second phase are to share slots with turn portions of the first phase, it often is desirable to provide a layer of insulation between the turn portions of the different phases. For example, in the case of some electric motor stators with portions of a first winding phase located along the bottom or closed end of a number of different slots and with portions of a different winding phase located along the top or open end of some of the same slots, insulative "separators" or slot separator wedges extend axially along the shared slots and separate the wire segments of the different phases; whereas slot closing wedges are disposed at the open end of the slots.
Needham et al U.S. Pat. No. 3,038,093 which issued June 5, 1962 shows, in FIG. 3 thereof, details of different parts of an electric motor such as, e.g., slot liners (or slot "cells"); separators (or slot separator wedges); and pegs (or slot closing wedges). Other patents that show stator assemblies and insulators that are incorporated therein are Phillips U.S. Pat. No. 2,998,540 of Aug. 29, 1961; Balke U.S. Pat. No. 2,778,964 of Jan. 22, 1957; and Walker U.S. Pat. No. 3,519,862 of July 7, 1970.
Equipment has been available long heretofore which has been used to reliably place slot separator wedges in selected slots of a magnetic stator core concurrently with the placement of side turn portions of a winding in the bottoms of the slots; or to place slot closing wedges along the slots while winding turn portions are placed therein. Equipment of the general type just mentioned (as well as processes related thereto) are described, for example, in Arnold et al U.S. Pat. No. 3,579,818 of May 25, 1971; Smith et al U.S. Pat. No. 3,831,255 of June 25, 1973; Hill U.S. Pat. No. 3,324,536 of June 13, 1967; Walker et al U.S. Pat. No. 3,694,887 of Oct. 3, 1972; and Morr U.S. Pat. No. 3,872,568 of Mar. 25, 1975. The equipment described in the just mentioned patents may be used, as desired, to push slot separator or slot closing wedges vertically upwardly or downwardly, horizontally, or at any desired angle of inclination or declination along magnetic core slots. As will be appreciated from a review of the just mentioned patents, wedges are loaded into a magazine having a number of slots aligned with a stator holding or locating station; and the wedges ultimately are pushed by elongate pushers into and along preselected ones of the core slots--usually concurrently with the placement of winding turns therealong.
Although the equipment just discussed has been widely used in the motor industry, other types of equipment and processes have also been used whereby windings are made and placed in core slots without reference to wedges (either of the slot separator or slot closing type), and wedges must subsequently be placed in the core slots after winding turn portions have already been accommodated therein.
For example, winding coils may be developed on a simple lathe-type of machine and then machine-placed or hand-placed in core slots. Alternatively, coils per se may be developed and then placed in core slots with processes and equipment of the type described in Mason U.S. Pat. No. 2,934,099 of Apr. 26, 1960; or Arnold U.S. Pat. No. 3,797,105 of Mar. 19, 1974. It will be understood that in these cases it is then usually necessary to effect wedge placement after placement of some or all of the winding turns.
One type of equipment that has been used heretofore for effecting subsequent wedge placement has, in effect, been generally similar to that shown in the above referenced Arnold U.S. Pat. No. 3,579,818; or Hill U.S. Pat. Nos. 3,324,536, and 3,694,887. However, when wedges only are to be placed; it is common practice to eliminate those portions of the previously known equipment that are provided in order to handle winding turns; and to use an end turn blocking or shaping mechanism that will establish or maintain a desired clearance between previously placed winding end turns and paths along which wedges are to be moved into slots of a core. Prior equipment and methods pertaining to subsequent wedge placing and with which we are familiar are characterized by short comings in that wedges (and particularly slot separator wedges) frequently can be misplaced or improperly positioned within one or more of the core slots. When this condition occurs, it is necessary to manually reposition the misoriented slot separator wedges or, in extremely aggravated cases, manually remove misoriented slot separator wedges and then manually place a new slot separator wedge along such slots.
It is our belief and understanding that unacceptable amounts of misorientation of slot separator wedges during placement along previously placed windings is caused partly by the fact that the wedges will tend to follow the previously placed wire segments. Thus, such segments have, in effect, led the separator wedges into a misoriented position. This problem is aggravated, it is believed, by the fact that slot wedges are made of a relatively slippery material (e.g., polyethylene terephalate, one commercially available form of which is sold under the name MYLAR by E. I. DuPont DeNemours and Company). The slot liners also are often formed of this same (or an equivalent) material and the separator wedges therefore tend to readily slide into any position directed by the winding turn segments.
Peters U.s. Pat. No. 3,805,357 of Apr. 23, 1974 illustrates one approach that may be followed when attempting to overcome the misorientation problem just described. The approach of Peters, however, would require equipment substantially more complex than the wedge placing mechanisms used heretofore. Moreover, it is most desirable that wedge placer methods and equipment be both simple and readily usable with cores (and thus wedges) of many different axial lengths.
It should now be understood that it would be desirable to provide new and improved methods and apparatus whereby the above described and other problems may be readily overcome.
Accordingly, it is a general object of the present invention to provide new and improved methods and apparatus whereby slot separator wedges of a predetermined length may be placed in slots alongside previously placed winding turn segments in such a fashion that a desired predetermined orientation of the wedges relative to the segments and slot walls will be reliably established and maintained.
It is a more specific object of the present invention to provide new and improved methods and apparatus whereby wedges are moved along predetermined core slots having previously placed wire segments therein, with the wedges being maintained away from the wire segments; and thereafter causing the wedges to move generally radially along such slots and into proximity with the wire segments.
It is another specific object of the present invention to provide new and improved apparatus and methods whereby wedges are moved axially along a slot and held in a slightly resiliently deformed condition; and thereafter released to assume a less deformed configuration adjacent to wire segments that have been placed in such slot prior to placement of the wedge.
Another object of the present invention is to provide new and improved methods and apparatus for placing slot separator wedges, with such apparatus and methods being relatively simple in nature but most reliable in operation.
Yet another object of the present invention is to provide new and improved apparatus and methods whereby separator wedges are pushed from one end thereof along guide means along core slots.
Although the present invention will be readily understood by persons skilled in the art after the following summary and detailed description are reviewed; persons less familiar with the art may find it desirable to review the above referenced patents for a better understanding of the background of the invention. For this reason, the disclosures of the above referenced patents are incorporated herein by reference. Of particular interest to features claimed by us are those portions of the above cited U.S. Pat. Nos. 3,579,818; 3,324,536; 3,831,255; 3,694,887; and 3,872,568; that relate to wedge making and wedge placing mechanisms, and the Peters U.S. Pat. No. 3,805,357.